M40 Rifle
The M40 is the bolt-action sniper rifle of the US Marine Corps, adopted in 1966 and in service in successive versions until the 2010s. The original rifle was a Remington Model 700 with a heavy barrel, walnut stock and Redfield scope; the Marines' own armorers at Quantico rebuilt it in the 1970s as the M40A1 with a fiberglass stock and Unertl scope, and later as the M40A3, A5 and A6. Marine scout-snipers used it in Vietnam, the Gulf War, Iraq and Afghanistan until the Mk13 Mod 7 replaced it.
Also known as M-40, M40, M40A1, M40A3, M40A5, M40A6
Origins
The M40 entered service for the US Marine Corps in 1966 as a sniper rifle. When the Marines went to Vietnam War in 1965, they had no standard sniper rifle; their scout-snipers used Winchester Model 70 target rifles and a few scoped M1903 Springfields. The Marine Corps wanted a single standard rifle and chose a commercial design. The original variant was based on the Remington 700 civilian bolt action rifle: a Model 700 with a heavy barrel in 7.62x51mm NATO, a walnut stock and a Redfield 3-9x variable scope. The first rifles were delivered in 1966 and sent straight to Vietnam.
Design & Construction
The Remington 700 action is a simple and strong bolt action with a two-lug bolt and a recessed bolt face, and it is known for its accuracy. The original M40's walnut stock swelled and warped in the Vietnamese heat and humidity, which changed the rifle's point of impact. So in the 1970s the Marine Corps rebuilt its rifles at the Precision Weapons Section at Quantico as the M40A1, with a McMillan fiberglass stock, a stainless-steel heavy barrel and a fixed 10x Unertl scope. The rifle has evolved into several other variants over the years: the M40A3 of 2001 with a new stock and Schmidt & Bender scope, the M40A5 with a detachable magazine and suppressor-ready muzzle, and the M40A6 of 2016 with a folding chassis stock. Every M40 was built by hand by Marine armorers, who bedded each action into its stock and test-fired each rifle for accuracy before it was issued.
Combat Use
In Vietnam the M40 served alongside the Winchester 70 with Marine scout-snipers, including at Battle of Khe Sanh in 1968, and gained a reputation for accuracy despite the stock problems. The M40A1 served in the Gulf War of 1991 and in Somalia, and the M40A3 and M40A5 served through the Global War on Terror in Iraq and Afghanistan, where Marine snipers made kills at ranges beyond 800 meters.
Legacy
The M40 was the Marine Corps sniper rifle for more than fifty years, before being replaced by the Mk13 Mod 7 in .300 Winchester Magnum from 2018. It is one of the longest-serving sniper rifles of any modern army, and a symbol of the Marine scout-sniper tradition. Its Army counterpart, the M24 Sniper Weapon System, was also built on the Remington 700 action. Genuine M40s are very rarely found outside government hands, but civilian clones built from Remington 700 actions are popular with collectors.
Sources
Senich, Peter R. The Long-Range War: Sniping in Vietnam. Paladin Press, 1994.
Chandler, Norman A., and Roy F. Chandler. White Feather: Carlos Hathcock, USMC Scout Sniper. Iron Brigade Armory, 1997.
Pegler, Martin. Sniper Rifles: From the 19th to the 21st Century. Osprey Publishing, 2010.
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